Sinusoidally Modulated Leaky-Wave Antenna for Millimeter-Wave Application

A millimeter-wave sinusoidally modulated (SM) leaky-wave antenna (LWA) based on inset dielectric waveguide (IDW) is presented in this paper. The proposed antenna, radiating at 10° from broadside at 60 GHz, consists of a SM IDW, a rectangular waveguide for excitation and a transition for impedance matching. Fundamental TE
₀₁
mode is excited by the IDW with the leaky wave generated by the SM inset groove depth. The electric field is normal to the metallic waveguide wall and thus reduces the conductor loss. As a proof of concept, the modulated dielectric inset as well as the dielectric transition are conveniently fabricated by 3-D printing (tan δ = 0.02). Measurements of the antenna prototype show that the main beam can be scanned from -9° to 40° in a frequency range from 50 to 85 GHz within a gain variation between 9.1 and 14.2 dBi. Meanwhile, the reflection coefficient |S
₁₁
| is kept below -13.4 dB over the whole frequency band. The measured results agree reasonably well with simulations. Furthermore, the gain of the proposed antenna can be enhanced by extending its length and using low-loss dielectric materials such as Teflon (tan δ <; 0.002).